Compositions comprising rubbers such as ethylene-propylene-diene rubber are most often opaque, even as relatively thin films. This is due in part to the necessary presence of opacity-inducing fillers (talc, clay, etc) in the rubber or rubber compositions, as well as the inherent incompatibility between additives such as polypropylene and the ethylene-rich rubber, having a significant refractive index difference and thus creating haze. Fillers such as talc are necessary in part because most EPDM rubbers are gummy and/or fluid and cannot be pelletized for easy feeding to the melt-blender. Thus, what is typically done in the industry is the EPDM is sold as a large bail, and the bail is shredded at the site of its compounding. Fillers are then added to the EPDM to allow for a controlled feeding of amounts of the EPDM to melt-blending devices.
What would be useful are elastomeric compositions that are transparent or translucent. Such compositions exist, such as styrenic block copolymer based compositions or urethane-based compositions, but these can be expensive. It would be desirable to use less expensive polyolefin-based materials in making a translucent composition.
Some translucent polyolefin-based compositions have been disclosed in US Patent Publication No. 2008/0032079, U.S. Pat. No. 7,094,837, U.S. Pat. No. 6,147,160, U.S. Pat. No. 5,115,030, and U.S. Pat. No. 4,603,158. Some of these publications solve the problem of having an elastic, strong and translucent composition by using a high ethylene-content EP rubber in a blend with polypropylene to form a blend or cured to form a vulcanizate (TPV). These can lack desirable properties such as low Compression Set, high elasticity, and, due at least to the thermoplastic/ethylene-rubber incompatibility, some haze or lack of translucence. The inventors have solved these and other problems herein.